How does js know that a user has jumped back to the browser from an app?

problem description

1. Select WeChat Pay on the payment page and click OK to jump to Wechat.
2. WeChat will wait five seconds to automatically return to the payment page.

question: how do I pop up a window to ask if the payment is successful when I return?

the environmental background of the problems and what methods you have tried

returning directly will not refresh the page;
has tried to pass the link and can jump, but the manager says that this way of opening a new page is not allowed.

Html5 javascript
Sep.23,2021

WeChat Pay is successful and will definitely update the payment status of an order record. You can query this value regularly on the page, without even asking the user whether the payment has been successful.

tried to pass the link and you can jump, but the manager said that this way of opening a new page is not allowed. Why is this not allowed? It can only be done by calling back the address

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3b043-2c252.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3b043-2c252.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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